B₄C-SiC quasi-binary and B-C-Si ternary composites were prepared by arc melting in argon atmosphere using B₄C, SiC, Si, B and C powders. Uniform lamella texture indicating eutectic reaction was observed at SiC molar content of 45 to 50mol% in the quasi-binary system. Free C and free Si co-precipitated at the C-rich and Si-rich side of the quasi-binary compositions, respectively. The thermoelectric figure of merit values (Z) of the B₄C-SiC composites were generally greater than those of the C-rich and Si-rich composites. The SiC-B₄C composites near the eutectic composition (40mol%SiC) showed the greatest Seebeck coefficient, electrical conductivity and Z values. The greatest ZT value of the B₄C-SiC composites (40mol%SiC) at T=1100K was about 0.2.